When it comes to sipping something that's heart-healthy, it's hard to beat black tea. That's the word from Japanese researchers who concluded that black tea may give a quick boost to blood flow to the heart, reports Reuters.

In a small study with 10 healthy men, the researchers from Osaka City University in Japan found that blood flow in the coronary arteries improved two hours after the men drank black tea, but the same was not true of a different caffeinated drink used for comparison. This is just one of many studies that shows tea is good for our hearts with positive effects on cholesterol, blood clotting, and blood vessel function. But in this latest study, something new was learned: Tea has an immediate beneficial effect by improving the dilation of the blood vessels, which in turn allows for better blood circulation.

Drinking at least two cups of tea a day may dramatically reduce a person's chances of dying following a heart attack, a study suggests.

How does black tea do this? Study co-author Dr. Kenei Shimada told Reuters that tea is rich in antioxidant compounds called flavonoids, and he suspects they improve the functioning of the lining of the blood vessels, which increases how much the vessels dilate in response to blood flow. "The results of this study suggest that black tea consumption has a beneficial effect on coronary circulation," the researchers reported in the American Journal of Cardiology.

Legend has it that Buddhist priests help spread the custom of tea drinking outisde of China.

BOSTON, Massachusetts (CNN) -- Drinking at least two cups of tea a day may dramatically reduce a person's chances of dying following a heart attack, a study suggests.

Researchers said they suspect properties found in black and green tea may be protecting the heart.

"The results were more dramatic than I anticipated," said Dr. Kenneth Mukamal, who led the study, which was published Monday in the American Heart Association's journal, Circulation.

"Even if the true effect of tea is less than what we found, it could still make a sizable difference in heart attack survival."

The heavy tea drinkers in the study -- those who drank two or more cups of tea a day -- had a 44 percent lower death rate following their heart attack, compared with nondrinkers. The study found even a benefit in moderate tea drinkers. Those who drank fewer than 14 cups a week had a 28 percent lower death rate.

In the study, researchers asked 1,900 heart attack survivors about their tea consumption before their heart problem and followed them for up to four years.

"The most important outcome after a heart attack is whether they lived or died," said Mukamal of Beth Israel Deaconess Medical Center in Boston. "This is a high-risk group of people who are prone to another heart attack or other heart events. To imagine that tea might lower this risk is very exciting."

Researchers said there's good reason to believe it's the flavonoids -- antioxidants found naturally in various foods derived from plants -- that are protecting the heart by relaxing the blood vessels so blood can flow more easily. There's also evidence to suggest flavonoids may prevent LDL cholesterol -- the so-called bad cholesterol -- from becoming really bad cholesterol.

Mukamal isn't making that recommendation yet.

"Those who've had a heart attack and have been worried about caffeine in tea should be reassured," he said.

The study did not ask patients about decaffeinated tea use, but Mukamal said there's no reason to believe caffeine makes a difference in the benefit. However, herbal teas would not provide the same benefits since the chemical makeup is different than that found in black and green tea.

Dark beer, wine and whiskey also contain flavonoids but in amounts lower than that found in tea.

"Ultimately I hope this work will spur on more research so we can find out the exact effect of tea on the heart," Mukamal said, "so one day we could give a tea prescription, along with aspirin and other medications following a heart attack. It seems there are no downsides to drinking tea."

By Alison McCook

During the study, researchers tested the urine of 14 healthy volunteers who drank five cups of chamomile tea every day for two weeks. They found that drinking tea produced changes in the urine that suggest there was an increase in a substance that helps the body fight off colds.

Tea drinkers also produced higher levels of a substance called glycine, which can ease muscle spasms. This finding may help support claims the tea can relieve menstrual cramps, the researchers note.

The study clearly shows that chamomile tea produces changes in the body. What remains unknown, study author Dr. Elaine Holmes told Reuters Health, is whether these changes are good or bad overall.

"There are good reasons why the tea may be beneficial, but these hypotheses require further testing," said the researcher, who is based at Imperial College London in the UK.

According to Holmes' report in the Journal of Agricultural and Food Chemistry, chamomile is used as an anti-inflammatory, sedative and ulcer-fighter. Research also suggests that chamomile may act as an antioxidant and antimicrobial.

However, so-called "natural" products are not without risk, experts warn. For instance, chamomile tea can cause a severe reaction in people allergic to ragweed. Chamomile can also affect the absorption of iron, Holmes noted.

During the study, Holmes and her team tracked urine samples from seven men and seven women who drank multiple cups of chamomile tea every day. The researchers also tested urine samples from the two weeks before and after participants' weeks of tea drinking.

The researchers found that when participants drank the tea, their urine showed significantly more hippurate, a substance that can act as an anti-inflammatory. Drinking the tea also increased urinary levels of glycine, which may relieve muscle spasms, perhaps explaining reports that chamomile can ease menstrual problems.

After participants stopped drinking the tea, glycine and hippurate stayed elevated for up to two weeks, which suggests the effects of chamomile tea may be long-lasting, the study authors note.

Since hippurate is produced by substances in the gut, "it would appear that chamomile, which is known to have antibacterial properties, has changed the bacteria living in the gut," Holmes said.

"Even two weeks after stopping the intake of chamomile tea, the urine profile did not return to the starting profile, and therefore, the effects of chamomile tea are prolonged," she added.

The study was funded by Oxford Natural Products plc, which develops plant-derived products.

By Jennifer Warner, WebMD Medical News

Jan. 26, 2005 -- Need another healthy reason to drink green tea? Aside from fighting heart disease, cancer, and other diseases, a new study shows that drinking green tea may also fight fat.

The study showed that people who drank a bottle of tea fortified with green tea extract every day for three months lost more body fat than those who drank a bottle of regular oolong tea.

Researchers say the results indicate that substances found in green tea known as catechins may trigger weight loss by stimulating the body to burn calories and decreasing body fat.

The findings appear in the January issue of the American Journal of Clinical Nutrition.

Black tea, oolong tea, and green tea come from the same Camellia sinensis plant. But unlike the other two varieties, green tea leaves are not fermented before steaming and drying.

Most teas contain large amounts of polyphenols, which are plant-based substances that have been shown to have antioxidant, anticancer, and antiviral properties.

However, green tea is particularly rich in a type of polyphenols called catechins. These substances have also been shown to have anti-inflammatory and anticancer properties, but recent research in animals show that catechins may also affect body fat accumulation and cholesterol levels.

In this study, researchers looked at the effects of catechins on body fat reduction and weight loss in a group of 35 Japanese men. The men had similar weights based on their BMIBMI (body mass index, an indicator of body fat) and waist sizes.

The men were divided into two groups. For three months, the first group drank a bottle of oolong tea fortified with green tea extract containing 690 milligrams of catechins, and the other group drank a bottle of oolong tea with 22 milligrams of catechins.

During this time, the men ate identical breakfasts and dinners and were instructed to control their calorie and fat intake at all times so that overall total diets were similar.

After three months, the study showed that the men who drank the green tea extract lost more weight (5.3 pounds vs. 2.9 pounds) and experienced a significantly greater decrease in BMI, waist size, and total body fat.

In addition, LDL "bad" cholesterol went down in the men who drank the green tea extract.

The catechin content varies by amount of green tea used and steeping time. But general recommendations, based on previous studies on the benefits of green tea, are at least 4 cups a day. Green tea extract supplements are also available.

Researchers say the results indicate that catechins in green tea not only help burn calories and lower LDL cholesterol but may also be able to mildly reduce body fat.

"These results suggest that catechins contribute to the prevention of and improvement in various lifestyle-related diseases, particularly obesity," write researcher Tomonori Nagao of Health Care Products Research Laboratories in Tokyo, and colleagues.

By RealAge

Did you know that most of the free-radical fighters in green tea never make it to your bloodstream? But there's a solution.

To get a better grasp on the healthy catechins in your green tea, flavor your cup with a squeeze of citrus juice.

Catechins -- the antioxidants in green tea famous for lowering your risk of chronic disease -- quickly lose their power in your intestine. In fact, as much as 80% of the catechins in green tea are never absorbed. The solution to boosting absorption, researchers recently found, is as simple as flavoring your tea with freshly squeezed and strained lemon, orange, lime, or grapefruit juice.

The vitamin C in citrus may help with absorption by increasing the acidity in your small intestine. Other unidentified substances in the juice probably lend a hand, too. Researchers found a 50-50 mix had the greatest catechin-preserving effect, and lemon did it best, closely followed by orange, lime, and, in last place, grapefruit.

If you do take steps to boost the power of your green tea, you may even get a few added benefits.

* It may help you lose weight. At least one study shows green tea can stimulate moderate weight loss.

* It may help keep your knees young and strong -- catechins fight inflammation and arthritis.

* It can help your skin look great if used in conjunction with an antioxidant cream. Dab it on.

* It can help you stay sharp -- try 2 cups a day to see benefits.

RealAge Benefit: Getting the right amount of antioxidants through diet or supplements can make your RealAge 6 years younger.

The relief from fatigue that tea provides is a big reason for its popularity. This is due to caffeine, and caffeine has been a matter of controversy. It is a stimulant that has been shown to speed reaction time, increase alertness, and improve concentration. The physical effects include stimulation of digestive juice, the kidneys, and the metabolism in ways that possibly help eliminate toxins. An increasing of mental alertness, shortening of reaction time, and improving efficiency of muscle action is brought about by caffeine's stimulation of the heart and respiratory system, bringing more oxygen to the brain.

There has been much concern in the United States recently about the possible dangers of caffeine. As regards tea, it should be noted that all types of tea contain less caffeine than coffee.

Caffeine tolerance varies greatly among individuals, and an excess of it is toxic. Some research has shown a possibility that caffeine can interfere with fetal development, including lowering birth weight and contributing to skeletal and other abnormalities. Until they reach the age of seven or eight months, babies cannot get rid of caffeine metabolites, and traces of caffeine can appear in breast milk too. Due to these concerns, pregnant and nursing mothers should limit or avoid any beverage with caffeine, including tea.

Black tea infused for 5 minutes yields 40-100 milligrams.

A 3-minute infusion produces 20-40 milligrams, or half as much.

Twenty cups of green tea yield 240 milligrams, or about 12 milligrams per cup.

By Daniel DeNoon, WebMD Medical News

April 21, 2003 -- Add germ fighting to the health benefits of tea. Sorry, java lovers: The crucial ingredient's in tea leaves, not coffee beans

Tea is extremely rich in chemicals called alkylamines. Lots of germs also carry these chemicals. Could there be a link? A research team led by Jack F. Bukowski, MD, PhD, of Boston's Brigham and Women's Hospital, took a look

Sure enough, test-tube studies showed that alkylamines gave a big boost to some of the most important immune cells in the human body. Once these gamma-delta T cells saw them, they were primed to go after germs.

Next, a real test. Eleven healthy, non-tea-drinking volunteers drank five or six cups -- about 21 ounces -- of Lipton tea every day for two or four weeks. Another 10 non-tea, non-coffee drinking volunteers drank five or six cups a day of Nescafe instant coffee.

Both groups of volunteers donated immune cells before and after drinking tea or coffee. When the gamma delta cells from coffee drinkers saw pieces of germs, nothing much happened. In contrast, immune cells from tea drinkers went wild. Just two weeks after starting tea drinking, cells from seven of the 11 volunteers jumped into action soon after sensing germs.

This health benefit of tea may go farther than fighting germs. The same kinds of immune responses are important in fighting cancer.

Alkylamines aren't just found in tea. There are smaller concentrations in foods such as mushrooms, apples, and wine.

"These data provide evidence that dietary intake of tea and perhaps other vegetables and fruits containing alkylamine ... may prime human gamma delta T cells that they can provide natural resistance to microbial infections and perhaps tumors," the researchers write.

By Jeanie Lerche Davis, WebMD Feature Reviewed By Brunilda Nazario, MD

Green tea, black tea, and oolong tea are all rich in antioxidants, part of your body's natural defense against disease.

Read the tea leaves, caffeine lovers. Tea is gaining ground over coffee. Even Starbucks is bucking up its tea menu. The health benefits of tea are one compelling reason: Green and black teas have 10 times the amount of antioxidants found in fruits and veggies, by one estimate.

Studies of humans and animals show that the antioxidants in black and green teas are highly beneficial to our health, says 82-year-old John Weisburger, PhD, senior researcher at the Institute for Cancer Prevention in Valhalla, N.Y.

"I've published more than 500 papers, including a hell of a lot on tea," says Weisburger, who drinks 10 cups daily. "I was the first American researcher to show that tea modifies the metabolism to detoxify harmful chemicals."

Green tea, black tea, oolong tea -- they all come from the same tea plant, Camellia sinensis. The leaves are simply processed differently, explains Weisburger. Green tea leaves are not fermented; they are withered and steamed. Black tea and oolong tea leaves undergo a crushing and fermenting process.

All teas from the camellia tea plant are rich in polyphenols, which are a type of antioxidant. These wonder nutrients scavenge for cell-damaging free radicals in the body and detoxify them, says Weisburger. "Astounding" aptly describes tea's antioxidant power, he tells WebMD. "Whether it's green or black, tea has about eight to 10 times the polyphenols found in fruits and vegetables."

Black and green both have different types of antioxidants than fruits and vegetables. Thearubigins, epicatechins, and catechins are among those listed in a USDA chart. All are considered flavonoids, a type of antioxidant. Brewed green and black teas have loads of those, the chart shows. (Herbal teas may also contain antioxidants but less is known about them, Weisburger says.)

"In my lab, we found that green and black tea had identical amounts of polyphenols," he tells WebMD. "We found that both types of tea blocked DNA damage associated with tobacco and other toxic chemicals. In animal studies, tea-drinking rats have less cancer."

Look at the world's big tea drinkers, like Japan and China. "They have much less heart diseaseheart disease and don't have certain cancers that we in the Western world suffer," says Weisburger.

"The scientific evidence about tea is evolving and I think it's compelling," Jeffrey Blumberg, PhD, of the Friedman School of NutritionNutrition Science and Policy at Tufts University, tells WebMD.

Tea is a great example of the past decade's research of antioxidants, he says. "There is a pretty consistent body of evidence suggesting there is a benefit to tea. Tea is a very rich source of a specific kind of antioxidant called flavonoids."

The detoxifying effect of these antioxidants protects cells from free radicals, the damage that can lead to blood clot formation, atherosclerosis, and cancer, says Weisburger.

The bulk of research shows that regular tea drinkers, people who drink two cups or more a day, have less heart disease and strokestroke, lower total and LDL (often called "bad") cholesterol, and that they recover from heart attacks faster.

Some laboratory tests also show that black and green tea may help boost metabolism to aid weight lossweight loss, block allergic response, slow the growth of tumors, protect bones, fight bad breath, improve skin, protect against Parkinson's disease, and even delay the onset of diabetes.

In a study involving bladder cancer cells, green tea extract seemed to make the cancer cells behave oddly. They matured sooner, bound together tightly, and had a hard time multiplying. Another study found that men who drank oolong tea plus green tea extract lost more weight and total body fat, compared with men who drank plain oolong tea. Also, the green tea drinkers had lower LDL cholesterolLDL cholesterol.

Other small studies have found that the antioxidants from drinking tea can help prevent skin cancer. There's also evidence that tea extracts applied to the skin (in a lotion) can block sun damage that leads to skin cancer.

All this research seems to suggest that if you want to do something good for yourself, drink tea. "It has no calories and lots of polyphenols. If you're drinking tea, you're not drinking soda -- that's a real benefit. Water doesn't give you those polyphenols," says Blumberg.

Weisburger recommends drinking six to 10 cups of black or green tea throughout the day, starting with breakfast. Switch to decaf tea midday, if you need to. "Flavonoids are unchanged by removal of caffeine," he says.

Originally published Feb. 9, 2004, Medically updated April 5, 2005.

Ask Dr. Ornish

Answer: Both green tea and black tea have been shown to reduce the risk of several types of cancers, particularly digestive tract and urinary tract cancers, as well as the risk of heart disease. In one study, those who drank more than two cups a day were 32% less likely to have cancers of the mouth, esophagus, stomach, colon, and rectum. They were also 60% less likely to have cancers of the urinary tract than those who never or seldom drank tea. And more of the beverage was apparently better. Four or more cups of tea per day lowered the risk of such cancers by 63%. In contrast, coffee drinking was not found to be related to the risk of these cancers.

Researchers at the Saitama Cancer Research Center in Komuro, Japan, also found that green tea may raise HDL-cholesterol levels.

Tea contains polyphenols, antioxidants that may be the source of its anticancer effect. Green tea contains a polyphenol known as epigallocatechin gallate (EGCg), which in animal tests has been shown to prevent the formation of tumors. Researchers at Purdue University found in laboratory tests that EGCg killed human breast cancer cells but did not kill noncancerous human breast cells.

Both green and black tea are made from the same plant, but are the result of different processing methods. Black tea is fermented, and green tea is not. Some studies also suggest that both green tea and black tea may enhance your immune function, but black tea has less EGCg than green tea. Green tea has less caffeine than black tea.

I would suggest avoiding caffeine for people who have irregular heartbeats, but the new research showing the substantial benefits of drinking tea may outweigh the modest amounts of caffeine in green tea. Also, you can find decaffeinated green tea and black tea.

© 2001 WebMD Inc. All rights reserved.

By Miranda Hitti, WebMD Medical News

July 6, 2005 -- The FDA has given a thumbs-down on a bid to label green tea as a cancer fighter.

Current scientific evidence from human studiesscientific evidence from human studies doesn't support the claim, says the FDA's Michael Landa.

Landa is the deputy director for regulations at the Center for Food Safety and Applied Nutrition. He wrote the FDA's response to a green tea company's proposed cancer-prevention claim.

Landa doesn't totally dismiss green tea. Future research will be considered, he says.

For now, he says it is "highly unlikely" that green tea cuts breast cancer or prostate cancer risk.

Landa also says there is "no credible evidence" supporting green tea as a fighter of other cancers, including lung, gastric, colon, rectal, pancreatic, esophageal, skin, ovarian, or liver cancers.

All tea comes from the same leaves, but processing methods produce different types of tea. White tea is the least processed tea type; it's made from buds and young leaves. Next is green tea -- which is made from more mature leaves -- and black tea.

Tea is packed with antioxidants, which have been studied for their potential against cancer and heart disease. The type of tea determines the amount and types of antioxidants.

The FDA's review only addressed cancer.

Green tea has been found to have cancer prevention activity in animal studies. The flavonoids found in tea are known for their ability to alter cell pathways that may lead to cancer.

Many green tea studies have been done on animals, or on cells in lab tests. Some have also tracked health among large groups of people who drink a lot of tea.

For instance, researchers unleashed antioxidants called phenols from tea on human breast cancer cells in a lab experiment. The tea phenols had a sizeable impact on breast cancer cell growth, the researchers said in April 2004.

Other experiments have targeted human prostate and bladder cancer cells. Those cells were placed in mice, where they were treated with a green tea extract.

The data on green tea reviewed by the FDA included only human studies.

Studies done on humans have inconsistent evidence. Some of those studies showed decreased cancer risk for breast and prostate cancers, but others didn't. A lot of the data were "weak and limited," says Landa.

Some research on stomach cancer -- done in Japan -- got benched because the disease and salt intake differs in Japan and the U.S., says Landa.

Some other foods bear FDA-approved health claims.

Packages of nuts and whole-oat foods can carry labels touting possible heart benefits.

Nuts got the nod from the FDA nearly two years ago. Oats were OK'd for the labeling back in 1997.

The FDA's standards for food claims aren't as strict as its approval process for new drugs.

SOURCES: News release, FDA. FDA, "Letter Responding to Health Claim Petition dated Jan. 27, 2004: Green Tea and Reduced Risk of Cancer Health Claim." WebMD Medical News: "Wine, Beer, Tea May Slow Breast Cancer." WebMD Medical News: "Green Tea's Record Against Cancer Grows." WebMD Medical News: "FDA OKs Nutty Heart Health Claim." Talk paper, FDA. The Linus Pauling Institute.

By Andrea Braslavsky, WebMD Medical News

Aug.17, 2000 -- Remember oat bran? It was supposed to help with digestion, prevent cancer, reverse heart disease -- you name it, oat bran did it. Until it more or less disappeared off the radar of our collective consciousness. Today, it seems that green tea is everywhere, being touted as capable of doing just about anything.

Recent scientific studies have indicated that green tea could protect against cancer, heart disease, and osteoporosis, as well as aid in weight loss. And you can't walk into a cosmetics store these days without bumping into a skin care product containing green tea. Many believe the tea in skin products can help ward off skin cancer and signs of aging.

But can green tea really be good for your skin? An article published in the August issue of the Archives of Dermatology says yes -- in theory.

"There may be some benefits of green tea in the human skin products," Hasan Mukhtar, PhD, and colleagues say in the article, which summarizes all the known information about green tea's effects on the skin. Mukhtar is a professor and the director of research in the department of dermatology at Case Western Reserve University in Cleveland.

Still, Mukhtar says, it's not clear whether the amounts of green tea found in the skin products now available are enough to have any benefit. In other words, don't run out and stock up on green tea masks, creams, and bubble baths just yet.

Green tea is consumed mostly in Asian countries, including India, Japan, Korea, and China; it's not quite as popular as its cousin, black tea, which is consumed by more than 75% of tea drinkers. Like black tea and oolong tea, green tea comes from the Camellia sinensis plant -- but unlike the other two varieties, its leaves are not fermented before steaming and drying; they remain fresh.

Mukhtar believes, as do others, that green tea's antioxidant property is key to its skin-protective qualities. "Of all the antioxidants known to mankind, the components of green tea are the most potent," says Mukhtar. "Antioxidants are those agents which can counteract the effects of oxidant radicals." Oxidant radicals -- or free radicals, as they are commonly called -- are byproducts of the body that can cause damage to cells and tissues. Antioxidants bind to the free radicals, deactivating them before they can cause harm.

Green, black, and oolong teas -- along with coffee, red grapes, kidney beans, raisins, prunes, and red wine -- contain large quantities of polyphenols. Polyphenols, which are a class of bioflavinoids, have been shown to have antioxidant, anticancer, antibacterial, and antiviral properties.

Most of the polyphenols in green tea are catechins. Catechins, which are antioxidants by nature, have also been shown to function as anti-inflammatory and anticancer agents. One of the major catechins in green tea has been shown to be the most effective agent against skin inflammation and cancerous changes in the skin.

In their review of the scientific literature, Mukhtar and his colleagues found evidence that the compounds in green tea protected mouse skin from cancer caused by sunlight. Additionally, his team conducted a few experimental studies on human skin, and found that the polyphenols in green tea also had anti-inflammatory and anticancer properties.

While acknowledging that antioxidants are important, Allan Conney, PhD, believes there may be more at work. Conney's lab is also trying to unravel the mechanism by which green tea protects against cancer, and is now looking at the effects of the caffeine. "In our studies, if we remove the caffeine from tea and feed the decaffeinated tea to mice at a moderate dose, it loses most of its effectiveness at inhibiting ... skin cancer," says Conney, director of the Laboratory for Cancer Research at Rutgers University College of Pharmacy in New Jersey.

By Mark Moran, MPH, WebMD Feature

June 4, 2001 -- Green tea, red tea, black tea -- by this time you may be swimming in tea and news about its purported ability to prevent cancer and heart disease. Now, American tea drinkers browsing the shelves of health food stores are liable to come upon a new one -- Rooibos tea, from South Africa.

"I drink it all day," says Jerry Hemelka, of San Pedro, Calif., who operates a trading company that imports Rooibos around the world. "It's excellent stuff, very mild with an aromatic taste."

Rooibos (pronounced ROY-boss) appears to be matching -- and possibly besting -- the health benefits claimed for other more established teas. A favorite among South Africans for years, the beverage is said by some to have 50% more antioxidants than are found in green tea. Antioxidants are the organic substances believed to scavenge "free radicals," the toxic by-product of natural biological processes that can damage cells and lead to cancer.

According to Hemelka, a long-time resident of South Africa, the tea is made from Aspalathus Linearis, an indigenous shrub that grows only in the mountainous region close to the Cape of Good Hope. Rooibos was discovered by the local inhabitants a long time ago, but commercially traded only since 1904, he tells WebMD.

Already commonplace in Japan, Germany, the Czech Republic, Holland, and England, Rooibos will soon sweep America, he predicts.

"It's totally unique and unknown in the United States," Hemelka says. "The United States could become the biggest market for Rooibos. If it takes off, we won't be able to supply enough to meet the demand."

Hemelka says there may be as many as 20 suppliers of Rooibos to the U.S. and more on the way. "A lot of people want to get on the bandwagon," he says.

Rooibos is sometimes used as substitute for milk with colicky babies, says Alvaro Viljoen, PhD, of the department of pharmacy at the University of the Witwatersrand. And the health benefits of Rooibos are bound to make it a favorite, he says: rich in antioxidants, rich in vitamin C, caffeine-free, and low in tannins, the residue in teas that can sometimes cause digestive problems.

"Rooibos has got all four of the buzzwords," Viljoen tells WebMD. "If you don't capture a market with those attractions, I don't think much else will sell it."

Experts agree that even without the advent of Rooibos, tea has become a veritable health phenomenon, as reports of its beneficial effects have spread in the media.

Nearly three million tons of tea are produced worldwide, according to the U.K.-based Tea Institute. Tea drinkers consumed nearly three cups a day in 1999, or a million more cups than the year before, according to the Institute.

A Medline search of articles on tea and its health effects yields scores of reports in the medical and scientific literature in the past several years. What emerges is a significant body of literature from animal studies showing that green tea may prevent heart disease and cancer. Other studies have also suggested that it may help avert osteoporosis, a condition characterized by fragile bones, and that it might have beneficial effects on skin when applied topically.

Experts emphasize that the primary thrust of scientific research has been on the pure tea products -- green, black, or oolong tea, derived from a plant called Camellia sinensis. All of the many other "herbal" or "medicinal" teas found in supermarkets and health food stores may be tasty, and may be good, bad, or indifferent for your health -- but they haven't been the focus of concentrated research, says John Weisburger, PhD, of the American Health Foundation.

"That's an area where consumers have a right to be a little frustrated," agrees Dave Ringer, PhD, scientific director for the American Cancer Society. "While the various mixtures of herbs and teas may be beneficial, they are not proven."

And not all the science has been favorable to tea. A report in the March 1 edition of The New England Journal of Medicine looking at green tea consumption in humans, found no effect on stomach cancers once adjustments were made for other factors that could affect risk. Those other factors included sex, age, history of stomach ulcer, use of tobacco or alcohol, and other dietary habits.

With this flood of tea and tea-related health news, consumers may want to know: What's real? What isn't? And what might be real, but is yet to be proven?

"Scientists can always say something remains to be proven," says Lenore Arab, PhD, professor of epidemiology and nutrition at the University of North Carolina at Chapel Hill School of Public Health.

Studying the effects of tea is difficult because the pattern of consumption varies from country to country -- and even within countries. And understanding the long-term health effects of tea requires long-term studies, she says.

In spite of the difficulties, there is a "large and convincing body of evidence that tea is chemo-preventive," Arab tells WebMD. "What has impressed me most recently is the accumulating evidence of tea's protective role in prostate cancer."

And now Arab says she and other tea researchers are seeing a protective effect against colon and rectal cancer among tea drinkers in Russia.

With regard to heart disease, Arab says a recent analysis pooling the results of 12 studies looking at tea consumption in a quarter million people, found that people who drink more green tea than others have less incidence of heart attack. Intriguingly, that effect was greater in Europe than in the U.S., she says.

Tea advocates say most of the health effects derive from "polyphenols," which are the antioxidants in tea. Weisburger explains that it is the oxidized form of cholesterol, for instance, that damages the surfaces of veins and arteries, leading to heart disease. "It turns out that polyphenols in tea prevent oxidation," Weisburger tells WebMD.

Weisburger was keynote speaker at this year's International Scientific Symposium on Tea and Human Health, sponsored by the U.S. Tea Council in Washington. A similar symposium will be held again next year, he tells WebMD.

The American Cancer Society has weighed in with a cautious statement on tea as a cancer preventive. Some animal studies have been shown to reduce risk, "but beneficial effects in people are not proven," according to a 1996 ACS statement on the subject.

"It's only in the last 10 year that Western science has tried to look at antioxidant activities of tea," says Dave Ringer, PhD, scientific program director at the ACS. "It's a young science. Generally, it is felt that tea can inhibit the initiation of cancer and delay its progression in animal studies. But we don't really have large well-controlled epidemiological studies to look at this yet [in humans], because you need to correct for the effects of other dietary components."

Dean Ornish, MD, says he believes some prominent medical journals, like The New England Journal of Medicine, have a bias against studies showing positive benefits of alternative treatments. Meanwhile, the "performance bar" for studies showing the positive effects of a pill or biomedical procedure is liable to be much lower, Ornish suggests.

Between a drug -- whose side effects may be known or unknown -- and a cup of tea, which is the more radical intervention, asks Ornish, director of the nonprofit Preventive Medicine Research Institute, in Sausalito, Calif., and clinical professor of medicine at the University of California School of Medicine.

Ultimately, the best reason to drink tea -- whatever its real benefits -- may be that it tastes good and there's virtually nothing wrong with it, he says.

"My attitude is if there is a potential benefit, even if not yet fully proven, and the downside is minimal if at all, why not do it?" says Ornish.

So drink up, by all means. Alvaro Viljoen, of South Africa, downs six to seven cups of Rooibos a day.

By Jennifer Warner, webMD Medical News

May 25, 2004 -- When it comes to tea, white may be the new "in" color. A new study shows white tea beats green at fighting germs and may help prevent common infections.

Researchers found an extract derived from white tea inactivated and slowed the growth of bacteria that cause streptococcous (strep) infections, pneumonia, and cavities in teeth.

"Past studies have shown that green tea stimulates the immune system to fight disease," says researcher Milton Schiffenbauer, PhD, a microbiologist and professor Pace University, in a news release. "Our research shows white tea extract can actually destroy in vitro the organisms that cause disease."

Schiffenbauer presented the study this week at the 104th General Meeting of the American Society for Microbiology in New Orleans.

In laboratory tests, researchers compared the effects of white and green tea extracts at inactivating viruses and preventing the growth of bacteria.

The study showed that the white tea extract was significantly more effective than the green at fighting germs.

In addition, the study showed adding white tea extract to conventional toothpastes enhanced their ability to kill germs and may help prevent cavities.

Researchers say the findings show that white tea extract may have antiviral and antifungal effects and may be used in the future to develop treatments to help prevent disease.

SOURCES: Schiffenbauer, M. "The Anti-Bacterial, Antifungal, and AntiViral Effect of White Tea," presented at the 104th General Meeting of the American Society for Microbiology, New Orleans, May 23-27, 2004. News Release, American Society for Microbiology.

By Jeanie Lerche Davis, WebMD Medical News

May 20, 2003 -- A cup of tea warms the soul -- and freshens your breath, and even fights infections. Two new laboratory studies add to mounting evidence of the health benefits of tea.

In the first study, conducted at Pace University, green tea extracts were mixed with several different kinds of bacteria, including those that cause strep throat and tooth decay. The researchers found that green tea was effective at fighting bacteria by inhibiting their growth.

"Our research shows tea extracts can destroy the organism that causes disease," says lead researcher Milton Schiffenbauer, PhD, a microbiologist and biology professor at Pace University in New York City, in a news release.

In fact, the same study suggests that green tea also helps toothpaste and mouthwash fight viruses -- by eliminating bacteria. Toothpaste or mouthwash alone demonstated little effectiveness at fighting viruses. However, by adding green tea extracts, the bacteria were nearly eliminated and the toothpaste was then able to fight off the viruses.

What's responsible for the health benefits of tea? Teas contain polyphenols, which are antioxidants that protect human cells from damage. Flavonids are a group of polyphenols that occur naturally in tea. It is suspected that high levels of these polyphenols in the body can fight viruses as well as cancer, including pancreas, colon, bladder, prostate, and breast cancer.

In the "bad breath" study, researchers combined black tea extracts with three species of bacteria (all linked with bad breath) in petri dishes for 48 hours. They compared the results with bacteria that sat alone.

In all cases, tea polyphenols inhibited the growth of bacteria by 30% and reduced the production of compounds that cause bad breath.

The study suggests that rinsing with black tea keeps plaque from forming and destroys acids that cause tooth decay.

"Besides inhibiting the growth of pathogens in the mouth, black tea and its polyphenols may benefit human oral health by suppressing the bad-smelling compounds that these pathogens produce," says lead researcher Christine D. Wu, PhD, professor of periodontics at the University of Illinois, Chicago, in a news release.

Both studies detailing health benefits of tea were presented at the annual American Society for Microbiology General Meeting held in Washington, D.C., this week.

SOURCES: Abstracts, American Society for Microbiology General Meeting, Washington, D.C., May 18-22, 2003. News release, University of Illinois, Chicago. News release, American Society for Microbiology.

By Daniel DeNoon, WebMD Feature

May 14, 2002 -- It doesn't matter whether it's oolong, green, or black. Years of moderate tea drinking builds strong bones, according to a new study.

Recent studies have shown that loss of bone can begin as early as the 30s -- especially in women. Osteoporosis -- or loss of bone -- is more common in women but occurs in elderly men as well. In women, the problem usually worsens after menopause when estrogen levels drop. Estrogen helps maintain strong, healthy bones. As you lose bone density, your risk of breaking a bone -- especially in the hip, spine, and wrist -- increases significantly.

For the report, published in the May 13 issue of the Archives of Internal Medicine, researchers gathered detailed dietary information from more than 1,000 Chinese men and women. About half of the people in the study drank tea at least once a week for at least six months. Their average age was 52 years.

Those that drank tea regularly for six to 10 years showed higher bone density in the spine than occasional tea drinkers, according to lead researcher Chih-Hsing Wu, MD, and colleagues of National Cheng Kung University Hospital, Tainan, Taiwan.

Those who drank tea for more than 10 years had even better bone density. It didn't seem to matter whether they drank green tea, oolong tea, or black tea. Few of the adults put milk in their tea. Milk contains calcium and vitamin D, both important for building and maintaining strong bones.

Tea is an important source of fluoride. Fluoride can slow osteoporosis.

Tea is rich in flavonoids, antioxidant compounds that improve bone density.

Animal studies show that tea extracts slow bone loss.

By Jennifer Warner, WebMD Medical News

May 6, 2002 -- Drinking tea may not only reduce your risk of developing heart disease, but it may also improve your chances of surviving longer after a heart attack. A new study shows heart attack victims who drank the most tea were the least likely to die in the years immediately following a heart attack.

Researchers say the findings add to a growing notion that the antioxidant-rich flavonoids found in black and green teas prevent heart disease. But this is the first study to suggest that drinking tea can actually protect the heart after damage has already occurred.

"The effects of tea on health have been widely studied, in part because tea contains flavonoids and other antioxidant compounds, but we don't know of any previous studies that considered the effect of tea consumption on survival after heart attack," says study author Kenneth Mukamal, MD, assistant professor of medicine at Harvard Medical School, in a news release. "Flavonoids are probably the best guess for the apparent benefits of tea in this study."

The findings are published in the May 7 issue of Circulation: Journal of the American Heart Association. For the study, researchers asked 1,900 heart attack survivors about their weekly consumption of caffeinated teas and followed them for about four years.

They found that those who reported drinking about two cups of tea per week were 28% less likely to die in the years immediately following their heart attack compared with non-drinkers. And the more tea the patients drank, the less likely they were to have died in the follow-up period. Those who reported drinking more than 14 cups per week had a 44% lower risk of death.

"We found that tea drinkers generally had lower death rates regardless of age, gender, smoking status, obesity, hypertension, diabetes or previous heart attack," says Mukamal in the release.

The study authors say there are several possible explanations for tea's heart-healthy effects. For example, a recent study found that black tea improved the ability of the blood vessels to relax in people with heart disease. In addition, flavonoids have been shown to affect the oxidation of the so-called bad LDL cholesterol, which may prevent heart attacks, and the substance may also have an anti-clotting effect.

Other foods rich in flavonoids include apples, onions, and broccoli.

Although this study did not differentiate from green or black tea consumption, black tea accounts for the majority of tea consumption in the U.S., and the patients were studied at American medical centers.

By Jennifer Warner, WebMD Medical News

Sept. 20, 2005 -- An antioxidant found in green tea may protect the brain and fight the memory-robbing effects seen with plaque deposits in Alzheimer's disease.

A new study shows high doses of the green tea ingredient -- known as epigallocatechin-3-gallate (EGCG) -- significantly reduced the formation of beta-amyloid proteins in the brains of mice that were altered to develop Alzheimer's disease. An abnormal buildup of beta-amyloid plaque in the brain is implicated in the nerve damage and memory loss seen in Alzheimer's disease.

EGCG is one of a group of antioxidants called flavonoids found in plants. They have been linked to a variety of health benefits seen in diets rich in fruits and vegetables, such as protecting against cancer or reducing the risk of heart disease.

In the study, published in the Journal of Neuroscience, researchers studied the effects of treating mice genetically altered to develop Alzheimer's disease with high doses of the green tea antioxidant.

After several months of daily injections of EGCG, the results showed that the nerve cells of treated mice generated as much as 54% fewer beta-amyloid protein than nontreated mice nerve cells.

"The findings suggest that a concentrated component of green tea can decrease brain beta-amyloid plaque formation," says researcher Jun Tan, PhD, MD, director of the Neuroimmunology Laboratory at the University of South Florida, in a news release. "If beta-amyloid pathology in this Alzheimer's mouse model is representative of Alzheimer's disease pathology in humans, EGCG dietary supplementation may be effective in preventing and treating the disease."

Green tea contains many different antioxidants. The researchers found other green tea antioxidants actually decreased EGCG's ability to reduce beta-amyloid protein production. Therefore, drinking green tea alone may not be enough to fight Alzheimer's disease.

"This finding suggests that green tea extract selectively concentrating EGCG would be needed to override the counteractive effect of other flavonoids found in green tea," says researcher Doug Shytle, PhD, of the University of South Florida, in the release.

Researchers say the dose of the green tea antioxidant humans would need to replicate the dose given the mice would be about 1,500 to 1,600 milligrams daily. That dose has already been studied in humans and found to be safe.

If further studies show treatment with EGCG can reduce memory loss in mice with Alzheimer's disease as well as reduce plaque formation, researchers say the next step would be clinical trials of the green tea antioxidant in humans to prevent and treat Alzheimer's disease.

By Martin Downs, WebMD Medical News

Sept. 8, 2003 -- New research shows that chemicals in green and black tea may be able to prevent skin cancer when applied to your skin. Eventually, these chemicals may be put into a lotion that could prevent skin cancer better than sun block alone.

Zigang Dong, MD, and colleagues at the University of Minnesota Hormel Institute in Austin, Minn., tested a solution containing chemicals called polyphenols, extracted from green tea, on live mice who were exposed to ultraviolet (UV) light. They also performed tests on skin cells from mice and humans cultured in the laboratory.

The study results, presented recently at the American Chemical Society annual meeting in New York, show that a protein called JNK-2 appears to be directly related to the development of skin cancer and that this protein can be blocked by the application of polyphenols. After the skin is exposed to UV light, levels of this protein rise and remain high. The researchers think that JNK-2 can cause a molecular chain reaction that makes normal skin cells become cancerous.

The experiments show green tea polyphenols reduce levels of JNK-2 in the skin and block the reaction that causes tumors to form.

Dong says that a lotion -- not a beverage -- would be the ideal way to deliver polyphenols to people's skin. Based on previous research, he says, a person would have to drink as many as ten cups of green tea a day in order to build up enough polyphenol molecules in the skin to produce any benefit.

Sun block works by filtering out UV rays before they penetrate the skin. A lotion containing polyphenols might help prevent skin cancer after exposure to the sun. "Hopefully we can dissolve the polyphenols in the lotion together with a sun block," Dong tells WebMD.

The researchers are already developing such a lotion, but their work is in the very early stages. "We don't have the data yet," Dong says. "We just began to do that."

Dong says he cannot speculate about how long it might take to develop the lotion. At this point, scientists are just beginning to learn what causes cancer, and more than anything, this study sheds light on how skin cancer develops. "Once we know that, we can prevent or treat cancer by targeting the specific genes or proteins," he says.

Nevertheless, Dong says, the study results can't be applied to melanoma -- the deadliest form of skin cancer. That's because no melanoma tumors developed on the mice in this study.

This study comes amid much new research about tea's potential cancer-fighting properties. Other research has shown that drinking green tea may prevent skin cancer, too.

Studies have shown that drinking tea may prevent cancer of the mouth, esophagus, stomach, lung, and prostate, but "when you ask the question whether people drinking more tea tend to have less cancer, then the result is not very clear-cut," C.S. Yang, MD, a cancer researcher at Rutgers University, tells WebMD.

"There are quite a few studies in Japan and China suggesting frequent tea consumption reduces the cancer rate of the stomach, and of the esophagus, and maybe some other sites," he says. "But also many other studies show there's no such beneficial effect. So we're really trying to figure out what's going on here."

By Charlene Laino, WebMD Medical News

April 5, 2006 (Washington) -- Potent chemicals found in tea can help ward off ovarian and breast cancers, new research suggests.

Broccoli and kale are also rich sources of cancer-fighting flavonoids, says Margaret Gates, a doctoral candidate at the Harvard School of Public Health who has been studying their link to ovarian cancer. Flavonoids are believed to have antioxidant and anti-inflammatory activity. Her research suggests that women who increase their consumption of kaempferol, a type of flavonoid, can lower their risk of ovarian cancer by nearly 40%.

A second study shows that women who consume a diet rich in other types of flavonoids - specifically, flavones, flavan-3-ols, and lignans -- can reduce their chance of developing breast cancer by 26% to 39%.

If you can't keep all those scientific names straight, no worries: It basically comes down to the same thing, the researchers tell WebMD.

For lowering ovarian cancer risk, "tea in particular may be important," Gates says.

For breast cancer protection, "tea again is the predominant contributor," Brian Fink, MPH, a doctoral candidate at the University of North Carolina at Chapel Hill.

Both new studies were presented at the annual meeting of the American Association for Cancer Research.

Gates analyzed data on 66,384 participants of the Nurses' Health Study, none of whom had ovarian cancer at the start of the study. Every few years, beginning in 1984, the women filled out detailed questionnaires that asked about their consumption of more than 120 foods.

Using the data, the researchers calculated each participant's intake of five different flavonoids -- myricetin, kaempferol, quercetin, luteolin, apigenin -- and of total flavonoids. Between 1984 and 2002, 344 of the women were diagnosed with ovarian cancer.

Gates says there was no link between total flavonoid consumption and ovarian cancer. Nor did myricetin, quercetin, luteolin, or apigenin significantly affect risk.

But the greater the consumption of kaempferol -- which the nurses got mostly from tea, broccoli, and kale -- the lower their chance of developing ovarian cancer.

So just how much kaempferol is enough? Gates says 10 milligrams to 12 milligrams a day, the amount found in four cups of tea or two cups of broccoli daily, appears to be protective. Both green tea and black tea will do the trick, she adds.

Gates says she'd like to see further research in this area. "If confirmed, flavonoid consumption would provide an important target for ovarian cancer protection," she says.

To look at the flavonoid-breast cancer link, Fink studied data from a large study of breast cancer rates and risk factors conducted among women living on Long Island, N.Y., in the mid-1990s. In 1996 and 1997, nearly 3,000 participants were interviewed at home about their lifestyle habits and given questionnaires that asked what they ate and how much they ate.

The study showed that postmenopausal women who consumed the most flavonoids were 46% less likely to develop breast cancer, compared with those who consumed the least. But the potent chemicals had no effect on risk in premenopausal women.

When the researchers looked at specific flavonoids in the postmenopausal women, they found that flavones reduce breast cancer risk by 39%, flavan-3-ols by 26%, and lignans by 31%.

In addition to tea, green salad, tomatoes, and apples are good sources of the breast cancer-fighting flavonoids, Fink says.

Other flavonoids, such as flavanones, isoflavones, and anthocyanidins, showed no relationship to cancer risk.

"Tiny differences in chemical structure could determine why one flavonoid is protective and one is not," he says. "More study is needed."

Cedric Garland, DrPH, a preventive medicine specialist at the University of California, San Diego, says flavonoids are a promising area of research for cancer prevention. He notes that flavonoids are available in supplement form.

The problem: "The research is only beginning to be done so we don't yet know how much to recommend," he tells WebMD.

In the meantime, your best bet may be a plate of broccoli washed down with a cup of tea.

By Salynn Boyles, WebMD Medical News

Nov. 2, 2001 -- You've probably read that green tea appears to protect against cancer. You may even know that its anti-cancer properties are attributed to an abundance of chemicals called polyphenols. But new research may explain, for the first time, how those chemicals fight tumors at a molecular level.

Using prostate cancer cell lines, researchers from H. Lee Moffitt Cancer Center in Tampa, Fla., found that polyphenols in green tea, and black and red teas for that matter, target a protein known to protect cancer cells from death. The research, along with several other studies evaluating the anti-tumor properties of food components, was presented this week at an international conference in Miami Beach, Fla.

The amino acid glycine was found to reduce breast tumor growth in rats. Apparently, it blocks the growth of new blood vessels that feed tumors. Glycine is manufactured in the body, but is also commercially available as a dietary supplement.

"These are very preliminary studies, but they are quite interesting," American Association for Cancer Research (AACR) President Waun Ki Hong, MD, tells WebMD. He says that human studies are needed to verify the findings, but this may represent an important contribution to the research. AACR co-sponsored the annual meeting along with the National Cancer Institute and the European Organization for Research and Treatment of Cancer.

In the green tea research, Aslamuzzaman Kazi, PhD, and colleagues found that polyphenols reduced the level of Bcl-XL protein in prostate cancer cell lines. Bcl-XL has been shown to protect cancer cells from death -- known scientifically as apoptosis

"The higher the concentration [of polyphenols] the more apoptosis," Kazi tells WebMD. "Epidemiological studies have shown that tea has anticancer activities. We wanted to try to understand the molecular mechanism of this action."

Studies in humans have, in fact, been inconclusive regarding the role of tea in preventing or slowing cancers. While some have shown a clear protective benefit, others have not. The most recent large study, published last March in The New England Journal of Medicine, found that drinking green tea did not lower the risk of developing stomach cancer in a group of Japanese subjects.

In the glycine study, researcher Zishan Haroon, MD, PhD, and colleagues at Duke University Medical Center, found high levels of glycine reduced breast tumor growth rates by 15% in rats by blocking the growth of new tumor-feeding blood vessels. The special diet also reduced wound-healing by 30%, which, Haroon tells WebMD, explains glycine's effect on tumors.

"Tumors and wounds have one very important thing in common -- they both produce new blood vessels through the same mechanism, known as angiogenesis," he says. If you can block one response, you can block the other, he says.

By Liza Jane Maltin, WebMD Medical News

April 23, 2002 -- It's already been shown to reduce the risk of heart disease and cancer, and now there's evidence that the miracle brew -- green tea -- may help prevent transplant failure in people with liver failure.

Right now, there are far more people in need of a liver transplant than there are suitable donor livers. The problem is that donor organs usually become available due to accidents, and quite often, accidents involve alcohol. Livers subjected to excess alcohol are not good candidates for transplantation. They are too fatty -- full of dangerous free radicals that make them susceptible to transplant failure, which can kill the recipient.

Free radicals are naturally produced in the body, and antioxidants help get rid of them.

Zhi Zhong, PhD, from the University of North Carolina at Chapel Hill, and colleagues looked at whether the powerful, free-radical scavenging antioxidants in green tea could alleviate some of the problems associated with fatty livers.

First, the researchers reproduced alcohol abuse in rats. After a bout of "binge drinking," the drunken rats were put to sleep and their livers removed. These fatty livers spent 24 hours in cold storage, and then some of them were bathed in a solution containing green tea extract. The team then transplanted a group of rats with these seemingly unfit organs and others with normal, healthy livers.

Only 13% of the rats that received untreated fatty livers survived, compared with 88% of those that received healthy livers. In contrast, survival rate was bumped up to 77% for rats that received a fatty liver bathed in green tea extract.

Green tea extract scavenges harmful free radicals in fatty livers and therefore could be an effective treatment to prevent failure of liver transplants, according to the researchers.

By Jeanie Lerche Davis, WebMD Medical News

April 20, 2004 -- Wine, beer, and tea appear to slow breast cancer growth, new research shows. It's more evidence that plant-based foods (or drinks) can positively affect health.

Grapes, grains, and tea leaves -- the main ingredients in these drinks -- contain phenols, natural compounds that have been shown to have protective effects against heart disease, cancer, viruses, and allergies. Phenols appear to protect cells, tissues, and arteries against the damaging effects of free radicals in the bloodstream. Free radicals are the by-products of cell processes that can damage cells.

However, drinking alcohol for health purposes is controversial -- especially for postmenopausal women. Regular, moderate amounts of alcohol have been shown to increase a woman's risk of breast cancer by affecting female hormone levels. Since postmenopausal women's bodies make less estrogen and progesterone, by drinking alcohol and altering the balance of hormones further, they may expose their breast cells to higher levels of estrogen. This may trigger the estrogen-sensitive breast cells to become cancerous.

In this study, researchers set out to examine whether compounds in these drinks could have breast cancer-fighting properties. In petri dishes, they first grew human breast cancer cells -- then individually exposed them to phenols from red wine, beer, and tea.

All three phenol compounds significantly affected breast cancer cell growth -- as early as 24 hours after exposure to the cancer cells, reports researcher Sandra Pinheiro-Silva, with the University of Porto in Portugal.

Phenols in all three drinks -- wine, beer, and tea -- markedly protected DNA from damage, which also causes cells to become cancerous.

Women are not advised to increase their alcohol intake to prevent breast cancer. More studies are necessary before any claim like that can be made.

By Alison Palkhivala, WebMD Medical News

April 5, 2001 -- Whether you enjoy a glass of tea or not, your skin may appreciate its medicinal effects. That's right. Researchers are investigating the natural properties of caffeine in tea to keep sun-damaged skin from becoming skin cancer.

Another group of scientists has developed an artificial enzyme that repairs sun-damaged DNA. Both treatments take advantage of the fact that skin cancer develops years or even decades after sun-induced skin damage occurs.

Skin cancer, the most common form of cancer, accounts for fully half of new cancer diagnoses in Western populations. More than a million new cases of skin cancer are reported in the U.S. every year. Although skin cancer usually develops later in life, most sun-induced damage, which is a major cause of skin cancer, happens earlier in life.

At the annual meeting of the American Association for Cancer Research, held last week in New Orleans, U.S. researchers reported that caffeine applied directly to the skin reversed sun-induced damage in mice.

"We've been studying the effects of green and black tea on chemically induced cancer and ultraviolet light-induced cancer in mice, particularly UVB light [from the sun]," senior author Allan H. Conney, PhD, tells WebMD. Conney is director of the Laboratory for Cancer Research at Rutgers University College of Pharmacy in Piscataway, N.J.

In previous studies, Conney and colleagues determined that green and black tea prevented sun-induced skin cancer when given orally to mice. The caffeine in the tea, they found, was the active component inhibiting cancer growth. Specifically, they found that caffeine increases skin cell death, suggesting injured skin cells die before cancer has a chance to develop in them.

Conney's team also found that oral caffeine increases levels of a special gene that is involved in suppressing tumor growth.

In their new study, Conney and colleagues investigated whether caffeine applied directly to sun-damaged skin would increase the death of damaged skin cells in mice.

"We exposed [mice] to UVB and then after the UVB exposure, we applied caffeine topically," he says. "We didn't want to have caffeine act as a sunscreen or work by some other mechanism because we wanted to explore what the biological effect of caffeine was immediately after exposure." They found that the topical caffeine did increase skin cell death.

Next, Conney and colleagues will look at whether topical caffeine prevents skin cancer from developing in mice exposed to UVB. Hopefully, within a year they will proceed with studies evaluating the effects of caffeine on sun-damaged human skin.

"These are only studies in mice, and whether [caffeine] has potential in human [skin cells] or not I don't know," Conney says.

In another study presented this week in San Diego at the annual meeting of the American Chemical Society, researchers report that they have produced an artificial enzyme that repairs DNA damage in skin cells that is caused by the sun.

Lead researcher Marco Jonas, PhD, tells WebMD that people known to be at high risk for skin cancer because of genetics, fair skin and eyes, or a history of sun worshipping could be screened later in life for the presence of sun damage to the DNA in their skin cells. Those with such damage could be treated with this molecule, or a similar one, to repair this DNA damage before it becomes cancerous. Jonas is a researcher at the University of Notre Dame in Indiana.

This research is still in its infancy, however. The researchers say it will be at least another four months before the enzyme is tested in DNA, followed by several years of laboratory and clinical trials.

According to senior researcher Olaf Wiest, PhD, an assistant professor of chemistry and biochemistry at Notre Dame, "The idea in principle is that this could be a 'sunscreen for years after.' There is a very long time lag between the occurrence of the damage [to the skin] and the actual skin cancer. ... [During this time,] you could try to go in there and repair the damage that has been done."

One drink--more than any other--will keep your brain young. And that drink is tea. Green tea or black tea. Hot tea or iced tea. It doesn't matter. Tea may be the brain's fountain of youth.

Regular consumption of either green or black tea seems to reduce the risk of age-related degenerative brain disorders, such as Alzheimer's disease, according to researchers from the Douglas Hospital Research Centre at McGill University in Canada. That's right. You may be able to protect your brain later from the ravages of dementia by drinking tea now.

How does tea do this? Catechins, an antioxidant in the tea, actually prevents neurons from dying, combating an underlying cause of Alzheimer's. Led by Rémi Quirion, the team used cultured nerve cells (also called neurons) and exposed them to amyloid, a protein believed to cause Alzheimer's disease. This molecule was toxic and caused cell death in the cultures; however, cell cultures that received the deadly amyloid followed by an administration of tea extracts and catechins were rescued and survived.

It's important to note the human clinical trials have not been conducted. Still, co-author Stéphane Bastianetto is encouraged. "This research does suggest that a regular consumption of tea, green or black, may reduce the risk of neurodegenerative disease such as Alzheimer's."

The best way to make a cup of tea: For a great afternoon pick-me-up, brew a cup of tea and make it extra rich in antioxidants. To do this, use more tea leaves per cup or use less water. Brew it longer, and stir the leaves as the tea brews.

By JOHN FAUBER

Coffee, tea or a cup of confusion?

When it comes to your heart, coffee has taken a couple of lumps in the last year, although in a recent large study it got a clean bill of health. Tea, on the other hand, consistently is portrayed as a heart-healthy beverage, although last month the Food and Drug Administration once again denied that claim.

Coffee and tea have been studied intensely in the last several years, and while medical science has yet to definitively decide how the popular beverages affect the heart, it is inching closer.

Genetics may be key.

Earlier this year, two studies suggested that the less coffee a person drinks, the better.

In March, a study that followed more than 3,000 coffee drinkers in Greece for two years, found troubling levels of inflammatory substances in their blood, compared with those who don't drink coffee.

In other studies, those substances have been associated with higher rates of heart attack and stroke, although the new study did not assess whether the coffee drinkers were at more risk.

The study, which was presented at the American College of Cardiology annual meeting, found that men who consumed more than a cup of coffee a day had 30% higher levels of a particular inflammatory substance in their blood, compared with non-coffee drinkers. For women, it was 38% higher.

Various other inflammatory substances also were elevated in the coffee drinkers.

"Maybe (coffee) is harmful when you consume high quantities," said lead author Christina Chrysohoou, a cardiologist with the 1st Cardiology Clinic at the University of Athens in a March interview. "Moderate consumption is the best."

Just before that study, another one found a troubling link between coffee consumption and non-fatal heart attacks in patients who had a specific genetic trait related to how quickly they metabolized caffeine. About 50% of the U.S. population has that trait.

That study, published in March in the Journal of the American Medical Association, involved 2,014 first heart-attack patients in Costa Rica.

Those who slowly metabolized caffeine and who drank two to three cups of coffee a day had a 36% greater risk of having a non-fatal first heart attack. For those who drank four or more cups, the risk was 64% greater.

However, for those who were genetically predisposed to rapidly metabolize caffeine, drinking up to three cups of coffee a day brought as much as a 22% reduction in heart attack risk.

Fill 'er up

More reassurance came from a huge prospective study published last month that essentially gave coffee, at least filtered coffee, a clean bill of health.

The study, which followed 128,000 men and women for up to 20 years, found no evidence that coffee drinking increased the risk of coronary heart disease.

"We basically have cleared coffee's name," said senior author Frank Hu, an associate professor of nutrition and epidemiology at the Harvard School of Public Health. "There is no hint of increased risk."

In fact, those who drank more than six cups a day had a reduced risk of heart disease, according to the study published in Circulation, a journal of the American Heart Association.

"We don't want to make too much of that," warned Hu, who said that finding could be due to chance.

Hu noted, however, that other research suggests that coffee may protect against diabetes, Parkinson's and gall stones. Earlier this month, a separate study in the Archives of Internal Medicine found that it may help prevent the liver disease alcoholic cirrhosis.

"It seems that coffee is more helpful than harmful," Hu said.

One caution, he said, is that boiled, unfiltered coffee may raise cholesterol, but nearly all coffee in the U.S. now is filtered.

Hu said the other big concern is high-calorie and high-fat coffee drinks.

"Too much sugar and cream may create some health concerns," he said.

While coffee appears to be fairly benign toward the heart, there are other reasons to limit consumption, said Paul Millea, an assistant professor of family medicine at the Medical College of Wisconsin who practices at Froedtert Hospital.

It can contribute to ulcers and gastroesophageal reflux disease, he said.

Beyond that, drinking large amounts of coffee may be a sign of another concern.

"If we are downing multiple cups of coffee a day, why is it?" he said. "Usually it's because of some hyperstressed lifestyle."

He recommends limiting consumption to one to two cups a day.

Liters, not cups

But what about green tea?

Last month, researchers at Yale University School of Medicine weighed in on the issue with a review article that looked at more than 100 studies on the health benefits of green tea.

More studies are needed, they said. But they pointed to what they called an "Asian paradox," which refers to lower rates of heart disease and cancer in Asia despite high rates of cigarette smoking.

They theorized that the 1.2 liters of green tea that is consumed by many Asians each day provides high levels of polyphenols and other anti-oxidants that may help protect them against smoking.

These compounds may work in several ways to improve cardiovascular health, including preventing blood platelets from sticking together and improving cholesterol levels, said the researchers, whose study appeared in the May issue of the Journal of the American College of Surgeons.

Specifically, green tea may prevent the oxidation of LDL cholesterol (the bad kind), which in turn, can reduce the build-up of plaque in arteries, the researchers wrote.

It may be difficult for Americans to consume as much green tea as Asians, but they can get greater amounts of antioxidants in their diet by drinking some green tea, as well as increasing consumption of dark fruits and vegetables, drinking moderate amounts of red wine and even eating some dark chocolate, said lead author Bauer Sumpio, a professor of vascular surgery at Yale.

"The collective intake probably is of significant protection to cardiovascular disease," he said.

Sumpio said what swayed him is laboratory research on cells showing that green tea can act in a way that prevents heart disease and cancer.

"For me, there is no downside to drinking green tea," he said. "It's not like red wine with the alcohol issue."

Sumpio and his co-authors concluded in the article that "the evidence is strong that green tea consumption is a useful dietary habit to lower the risk [for] and treat a number of chronic diseases. . . . The consumption of six to 10 cups of tea per day might constitute an aid to increased health, longevity and quality of life."

However, the FDA isn't convinced.

Last month, after reviewing 107 studies, it concluded there was no credible evidence to support the claim that green tea reduced cardiovascular disease risk factors.

The statement came in a letter denying a request by a tea company to make heart health claims about green tea.

A conservative approach

The problem with many tea and coffee studies is that they usually look for associations between the beverages and heart disease risk, said James Stein, a cardiologist with the University of Wisconsin Hospital and Clinics.

It may be that coffee and tea drinkers are more likely to engage in other activities that can affect their heart health. For instance, coffee drinkers are more likely to be smokers. Green tea drinkers may be more likely to eat lots of fruits and vegetables.

In countries such as Japan, green tea drinkers also may consume much higher amounts of raw fish or foods such as seaweed, added Millea, of the Medical College.

Researchers try to adjust for those and other activities, but it is difficult to correct for everything that might have an effect.

And the studies do not assess individual susceptibility to the effects of caffeine, said Stein, an associate professor of cardiovascular medicine.

Clearly some people are better off if they do not consume caffeine, he said. That includes people with heart disease, high blood pressure and people who have had strokes.

Caffeine, at least in the short term, raises blood pressure and heart rate and can constrict arteries, he said.

"(Caffeine) could precipitate a plaque rupture and lead to heart attack," Stein said.

Stein acknowledged that coffee contains flavonoids that have been associated with better heart health, but he tells his patients to limit their coffee to one cup a day.

He said the research on green tea looks promising, but has yet to prove a clear heart benefit, although it certainly is healthier than drinking soda, he said.

"We've been arguing for two decades whether caffeinated (coffee) is better than decaf and whether green tea is better than black," he said. "We don't know if long-term use is really helpful or not.

"The conservative approach drinking these beverages in moderation will be the prevailing dogma for quite a while."

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